"The Duke of Edinburgh had a good night," a Buckingham Palace spokesperson told the AFP news agency on Saturday morning, adding: "There will be some members of the family visiting him this morning in hospital."

The Queen left the royal estate at Sandringham in Norfolk by helicopter at 10.35am on Christmas Eve and was driven to the hospital in a motorcade, joined by Prince Edward, Earl of Wessex.

Prince Charles - joined by his wife Camilla, Duchess of Cornwall - arrived at the hospital later on Saturday morning, and Princess Anne and Prince Andrew have also been to see their father.

Prince Harry, Prince William and the Duchess of Cambridge arrived at Sandringham on Saturday afternoon but are not thought to have been to see Prince Philip yet.

The 90-year-old duke, who is believed to be spending a second night in hospital, is said to be in "high spirits".

British prime minister David Cameron is being kept informed, according to a Downing Street spokesperson, and wished the duke a speedy recovery.

Prince Philip was treated under local anaesthetic with a coronary stent procedure described as "minimally invasive" by the palace, which added that he will stay in hospital under observation "for a short period".